Cerebral salt-wasting syndrome. We need better proof of its existence.

It is widely believed that the cerebral salt-wasting syndrome (CSWS) exists as an entity distinct from the syndrome of inappropriate ADH secretion, and that it is characterized by evidence of severe renal salt wasting that results in volume depletion and hyponatremia. Proof of the existence of CSWS as an entity requires documentation of renal salt wasting and volume depletion. The present review has been undertaken to examine the evidence that the CSWS is a separate entity. In this effort, we have discussed various methods of documentation of volume depletion, and then reviewed reported cases of CSWS to determine whether volume depletion and renal salt wasting have been clearly demonstrated. Our review has led us to conclude that not one case of purported CSWS has demonstrated clear evidence of volume depletion and renal salt wasting. If renal salt wasting had been proven in these cases, we would conclude that the likely site of renal salt transport was the proximal tubule. The proximal site of salt transport defect has been suggested by the absence of hyperreninemia and hypokalemia, which would be a distinguishing feature of Bartter's syndrome and Gitelman's syndrome.